package security;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;


import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;


/**
 *AES security
 */
public class AES {
	public static String keys="sdjnhhxkjyxgsthisisvsktiantianhappy";


 /**
 * AES加密算法
 */
 public AES() {
 }
 
 
 /** 
 * 加密 
 * @param content 需要加密的内容 
 * @param keyWord  加密密钥 
 * @return byte[]  加密后的字节数组
 */  
 public static byte[] encrypt(String content, String keyWord) {  
        try {             
                KeyGenerator kgen = KeyGenerator.getInstance("AES");
                SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG" );  
                secureRandom.setSeed(keyWord.getBytes());  
                kgen.init(128,secureRandom);  
                SecretKey secretKey = kgen.generateKey();  
                byte[] enCodeFormat = secretKey.getEncoded();  
                SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");  
                Cipher cipher = Cipher.getInstance("AES");// 创建密码器  
                byte[] byteContent = content.getBytes("utf-8");  
                cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化  
                byte[] result = cipher.doFinal(byteContent);  
                return result; // 加密  
        } catch (NoSuchAlgorithmException e) {  
                e.printStackTrace();  
        } catch (NoSuchPaddingException e) {  
                e.printStackTrace();  
        } catch (InvalidKeyException e) {  
                e.printStackTrace();  
        } catch (UnsupportedEncodingException e) {  
                e.printStackTrace();  
        } catch (IllegalBlockSizeException e) {  
                e.printStackTrace();  
        } catch (BadPaddingException e) {  
                e.printStackTrace();  
        }  
        return null;  
 }
 
 /**
 * @param content 需要加密的内容
 * @param password 加密密钥
 * @return String  加密后的字符串
 */
 public static String encrypttoStr(String content, String password){
 return parseByte2HexStr(encrypt(content,password));  
 }
 
 /**解密 
 * @param content  待解密内容 
 * @param keyWord 解密密钥 
 * @return  byte[]
 */  
 public static byte[] decrypt(byte[] content, String keyWord) {
        try {  
                 KeyGenerator kgen = KeyGenerator.getInstance("AES");  
                  SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG" );  
                 secureRandom.setSeed(keyWord.getBytes());  
                 kgen.init(128,secureRandom);  
                SecretKey secretKey = kgen.generateKey();  
                 byte[] enCodeFormat = secretKey.getEncoded();  
                 SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");              
                 Cipher cipher = Cipher.getInstance("AES");// 创建密码器  
                cipher.init(Cipher.DECRYPT_MODE, key);// 初始化  
                byte[] result = cipher.doFinal(content);  
                return result; // 加密  
        } catch (NoSuchAlgorithmException e) {  
                e.printStackTrace();  
        } catch (NoSuchPaddingException e) {  
                e.printStackTrace();  
        } catch (InvalidKeyException e) {  
                e.printStackTrace();  
        } catch (IllegalBlockSizeException e) {  
                e.printStackTrace();  
        } catch (BadPaddingException e) {  
                e.printStackTrace();  
        }  
        return null;  
 }
 
 /**
 * @param content 待解密内容(字符串)
 * @param keyWord 解密密钥
 * @return byte[]
 */
 public static byte[] decrypt(String content, String keyWord) {
  return decrypt(parseHexStr2Byte(content),keyWord);  
 }
 
 /**将二进制转换成16进制 
 * @param buf 
 * @return  String
 */  
 public static String parseByte2HexStr(byte buf[]) {  
        StringBuffer sb = new StringBuffer();  
        for (int i = 0; i < buf.length; i++) {  
                String hex = Integer.toHexString(buf[i] & 0xFF);  
                if (hex.length() == 1) {  
                        hex = '0' + hex;  
                }  
                sb.append(hex.toUpperCase());  
        }  
        return sb.toString();  
 }
 
 /**将16进制转换为二进制 
 * @param hexStr 
 * @return  byte[]
 */  
 public static byte[] parseHexStr2Byte(String hexStr) {  
        if (hexStr.length() < 1)  
                return null;  
        byte[] result = new byte[hexStr.length()/2];  
        for (int i = 0;i< hexStr.length()/2; i++) {  
                int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16);  
                int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16);  
                result[i] = (byte) (high * 16 + low);  
        }  
        return result;  
 }  


 public static void main(String[] args) {  
  
  String content = "guest";  
  String Key = keys;  
  
  //加密
  System.out.println("加密前：" + content);
  String encryptResult = encrypttoStr(content, Key);
  
  System.out.println("加密后：" + encryptResult); 
  
  //解密  
  byte[] decryptResult = decrypt(encryptResult,Key);  
  System.out.println("解密后：" + new String(decryptResult)); 
 }//end main
}//end class

